micro chaoter 8
True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.
False
True or false: Ultraviolet rays are chemical mutagens.
False
True or false: When an Hfr cell transfers chromosomal DNA to a recipient cell, it does not need to produce an F pilus.
False
A bacterial cell described as______________ can take up DNA from the surrounding environment.
competent
Cells that have the ability to take up DNA from the environment are called ______ cells. pathogenic recombinant immunogenic competent
competent
The F or fertility plasmid contains genes that are required for bacterial ______. transduction conjugation competence transformation
conjugation
Which of the following plasmids are self-transmissible? conjugative plasmids only neither conjugative nor mobilizable plasmids mobilizable plasmids only both conjugative and mobilizable plasmids
conjugative plasmids only
Conjugation in bacteria requires ______. formation of a biofilm matrix the isolation of chromosome fragments the presence of bacteriophages contact between donor and recipient cell
contact between donor and recipient cell
True or false: Vertical gene transfer is the transfer of genes from one organism to another in a population, while horizontal gene transfer is the transfer of genes from parent cell to progeny.
false
Genes into which transposons "jump" are usually ______ by the event. activated unaffected inactivated
inactivated
A(n)_______________ _______________ is a large segment of a cell's genome that has clearly originated in a different species.
genomic island
An auxotroph can be isolated from a prototrophic parent strain by ______ selection. direct degenerate differential indirect
indirect
A(n)___________________ is a change in the nucleotide sequence of DNA that is passed on to daughter cells.
mutation
A base substitution that leads to the creation of a stop codon is called a(n)______________mutation.
nonsense
______ are segments of DNA that can move from one location to another in a cell's genome. Plasmids Transcripts Mutagens Transposons
Transposons
True or false: The native or wild type strain describes the typical phenotype of strains isolated from nature.
True
Which of the following types of radiation are mutagenic? Ultraviolet rays Infrared rays X-rays
Ultraviolet rays X-rays
A mutant that requires a growth factor is a(n) ______. autotroph heterotroph auxotroph prototroph phototroph
auxotroph
A mutant which needs a particular nutrient to grow which the normal strain does not is called a(n)_________.
auxotroph
A(n)__________________ is a virus that infects bacteria, and some can transfer bacterial genes from a donor cell to a recipient cell.
bacteriophage
An origin of transfer is encoded by _______. both conjugative and mobilizable plasmids neither conjugative nor mobilizable plasmids mobilizable plasmids only conjugative plasmids only
both conjugative and mobilizable plasmids
When describing conjugation in Gram-negative bacteria, a donor cell with an F ______ is considered F+, while that without this structure are termed F-. fimbria flagellum chromosome plasmid cilium
plasmid
Cancer-causing chemicals are called_________________
carcinogen
Plating bacteria in duplicate patterns on both a nutrient agar plate and a glucose-salts agar plate is an example of_____________ plating.
replica
Random genetic changes that result from normal cellular processes are ______. spontaneous mutations synonymous mutations induced mutations
spontaneous mutations
Bacteria such as E. coli are an excellent model system for genetics studies because they can quickly grow to high densities, allowing us to screen for rare genetic events. These can give rise to different_____________ , which are genetic variants withing a species.
strains
The process of bacterial__________________ involves the uptake of "naked" DNA by competent bacterial recipient cells.
transformation
In prokaryotes, genes can be transferred from a donor to a recipient via three different mechanisms:_________ ,____________ , and_____________________ .
transformation transduction conjugation
"Jumping genes," or____________ , can move within a cell without specificity as to where they ultimately insert.
transposons
Mutagens that are DNA segments that can insert into genes and thereby inactivate them are called ______. thymine dimers intercalating agents transposons alkylating agents
transposons
What is a prophage? a mobile genetic element that carries antibiotic-resistance genes bacterial virus that contains a plasmid another term for a virus that can infect bacteria viral DNA that has been integrated into a bacterial chromosome
viral DNA that has been integrated into a bacterial chromosome
True or false: Plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells.
False
Which of the following mutations frequently results in the production of a shortened and non-functional protein because a different set of codons is translated? Point Silent Base substitution Nonsense Missense Frameshift
Frameshift
_______________mutations are generally the most harmful to cells because they change all of the codons downstream of the mutation.
Frameshift
Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell? Serotype Genotype Haplotype Phenotype
Genotype
Which of the following describes an organism's observable characteristics? Phenotype Haplotype Genotype Serotype
Phenotype
Which process requires visible light to repair DNA damage caused by ultraviolet light? Photoreactivation Excision repair Photolysis
Photoreactivation
__________________are circular pieces of bacterial DNA that do not usually encode information essential to the life of a cell.
Plasmids
Protection against the toxic effects of antimicrobial compounds or heavy metals is often encoded on plasmids called ____________ plasmids.
R
______________________is the change of a mutated genetic sequence back to its original, non-mutated form.
Reversion
Which of the following are sources of "naked" DNA? Contained in bacteriophages Secreted into the environment by bacteria Contained within bacteria that lack cell walls Lysed (burst) bacterial cells
Secreted into the environment by bacteria Lysed (burst) bacterial cells
__________________are DNA segments that increase the rate of mutations by inserting themselves into genes and inactivating them.
Transposons
True or false: Incorporation of an incorrect nucleotide in a molecule of DNA results in a distortion of the DNA helix that can be detected by repair enzymes.
True
Chemical mutagens can cause two types of mutations:___________ substitutions and ___________ mutations.
base; frameshift
Mutagens that modify nucleobases change their___________ -__________ properties.
base; pairing
The chance that a gene will undergo a mutation when a cell replicates its DNA prior to cell division is ______. more than 10-12 less than 10-1 between 10-1 and 10-4 between 10-4 and 10-12
between 10-4 and 10-12
A plasmid that can directs its own transfer from donor to recipient cells is called a(n)_______________ plasmid.
conjugative
Ultraviolet radiation causes a very specific type of DNA damage called ______. double-strand breaks base analogs thymine dimers transduction recombination
thymine dimers
Plasmids, transposons and phage DNA are all examples of ______. conserved core genetic sequences mobile genetic elements
mobile genetic elements
The total set of mobile genetic elements is called a(n)_______________ .
mobilome
A_________________ is an agent that induces changes in DNA.
mutagen
Genetic change in bacteria occurs through which two mechanisms? mutation vertical gene transfer horizontal gene transfer
mutation horizontal gene transfer
Chemical mutagens that modify ______ increase the odds of incorrect nucleotide incorporation during DNA replication. amino acids monosaccharides pentose sugars nucleobases
nucleobases
Many DNA polymerases have the ability to detect and repair their own errors in nucleotide incorporation. This ability is called______________ .
proofreading
Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by__________ by DNA polymerase and by ______________repair.
proofreading; mismatch
The majority of transposons contain _______ terminators. replicational translational transcriptional
transcriptional
Which of the following are possible outcomes of a base substitution? thymine dimer mutation synonymous mutation nonsense mutation frameshift mutation missense mutation
synonymous mutation nonsense mutation missense mutation
The mechanism by which bacterial DNA is moved from one bacterium to another by a bacteriophage is called_____________ .
transduction
Which of the following are the three main methods of gene transfer in bacteria? transduction transformation competition conjugation transposition translocation
transduction transformation conjugation
In insertion sequences, the__________ gene (the only gene) is flanked by____________ repeats.
transposase inverted
Which of the following are examples of mobile genetic elements? transposons plasmids chromosomal DNA phage DNA genomic islands
transposons plasmids phage DNA genomic islands
When some species of bacteria reach a certain density or when nutrients are in short supply, they ______. turn on genes required for competence begin nitrogen and carbon synthesis signal other cells to lyse
turn on genes required for competence
If DNA acquired through horizontal gene transfer is not a replicon, then a process called_____________ recombination must occur for that DNA to be passed on to daughter cells.
homologous
Consider a base substitution mutation that occurs in a codon that specifies the amino acid tryptophan. If it leads to a different amino acid, the mutation is called____________ mutation, and if the resultant codon is a stop codon, then the mutation is termed a(n)____________mutation.
missense; nonsense
DNA in the environment that is not contained within a cell or virus is called___________________ DNA.
naked
An organism that does not require growth factors is called a(n)__________ .
prototroph
The integration of a region of DNA into a segment that does not have extensive similarity in nucleotide sequence is called ______. horizontal gene transfer specialized transduction homologous recombination non-homologous recombination generalized transduction
non-homologous recombination
During_______________ recombination, a segment of DNA inserts into the cell's genome, a process that does not require a similar nucleotide sequence in the region of recombination.
nonhomologous
Genomic islands that encode disease-causing factors such as exotoxins, capsules, and adherence factors are called ___________ islands.
pathogenicity
The repair of thymine dimers by enzymes that break the covalent bonds between the dimers is called ______ repair. mismatch photoreactivation excision proofreading sos
photoreactivation
Donor and recipient bacterial cells are connected by a sex ______ during conjugation. membrane pilus fimbria cilium receptor
pilus
An organism that has the same nutritional requirement as the wild type is said to be a(n) ______. autotroph prototroph phototroph heterotroph auxotroph
prototroph
A base substitution that results in a codon that still codes for the wild type amino acid is called a(n) ______ mutation. missense deletion synonymous insertion frameshift
synonymous
Which of the following plasmids encodes all the necessary genetic information for transfer from one bacterial cell to another? Conjugative plasmids only Mobilizable plasmids only Both conjugative and mobilizable plasmids
Conjugative plasmids only
A bacteriophage consists of a genome made up of DNA or____________ , surrounded by a coat made up of _______________.
RNA; protein
A large segment of a cell's genome that originated in other species is called a(n) ______. fertility factor genomic island virulence factor genomic imprint genomic library
genomic island
Transduction exists in two kinds. What are they? nonspecific localized specialized generalized specific compartmentalized
specialized generalized
Variation in the color of corn kernels, as described by Dr. Barbara McClintock, is an example of the process called____________.
transposition
An organism that has a mutation is called a______________ .
mutant
True or false: Alkylating agents typically cause frameshift mutations.
False
True or false: A point mutation involves any substitution of a single nucleotide.
True
_____________ _____________structurally resemble nucleobases and can be mistakenly used when cells make nucleotides, which are then incorporated by DNA polymerase into DNA.
base; analogs
Mutant cells in bacterial cultures can be isolated by___________ selection and _________selection methods.
direct; indirect
A transducing particle carries ______. donor cell DNA phage DNA and recipient DNA phage DNA recipient cell DNA
donor cell DNA
A transducing particle carries ______. recipient cell DNA phage DNA phage DNA and recipient DNA donor cell DNA
donor cell DNA
In ___________ gene transfer, DNA moves from one organism to another, while in_______________ gene transfer, DNA is passed from a parent cell to its progeny.
horizontal; vertical
A(n)_____________mutation occurs if a single base pair is changed during DNA synthesis.
point
If a scientist is working with bacteria that have the typical phenotype of those isolated from nature, the bacteria are considered to be ______ type. natural normal wild
wild
The native or___________ _______________ strain describes cells that carry non-mutated DNA.
wild; type
Which of the following are systems bacteria can use to protect against invading DNA? polymerase chain reaction immunoglobulin formation restriction-modification CRISPR microarrays
restriction-modification CRISPR
The Ames test measures the effect of potential carcinogens on the____________ rate of a histidine-requiring Salmonella auxotroph.
reversion
In the Ames test, a control plate is used to show that reversion is due to the test chemical rather than to ______. thymine dimers spontaneous mutation rat liver enzymes glucose-salts medium
spontaneous mutation
When DNA is transferred from an Hfr cell to a recipient cell, the recipient _______. stays an F- cell becomes an F+ cell becomes a competent cell becomes an Hfr cell
stays an F- cell
DNase is added to a mixture of donor DNA and recipient. If the donor DNA is naked, what will happen? The recipient will be unable to acquire that DNA via transformation. The recipient will be transformed by the naked DNA. The DNase will degrade the recipient's chromosome.
The recipient will be unable to acquire that DNA via transformation.
The distortion of DNA by thymine dimers directly blocks which of the following cellular processes? Transcription Replication Translation Respiration
Transcription Replication
In conjugation in E. coli, an Hfr cell refers to ______. a cell with an intact F plasmid which is separate from the chromosome a cell in which the F plasmid has been degraded by DNase a cell that has combined with the other cells by sexual reproduction a cell that has donated its F plasmid to a recipient cell a cell in which the F plasmid has been integrated into the cell chromosome
a cell in which the F plasmid has been integrated into the cell chromosome
In bacteria,_______________ refers to DNA transfer requiring cell to cell contact.
conjugation
Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of ______ selection. indirect differential direct degenerate
direct
During DNA replication, the template strand can be distinguished from the newly synthesized strand by the presence of ______________ groups on certain nucleobases. This is very important for mismatch repair.
methyl
A base substitution that results in a change in the amino acid encoded is called a(n) ______ mutation. frameshift silent deletion missense nonsense
missense
A(n)_____________mutation is a base substitution that changes the codon to one that specifies a different amino acid.
missense
Genes that vary considerably among strains of a species are likely to be ______. mobile genetic elements auxiliary genetic elements the core genome the pan genome
mobile genetic elements
Mutations are rare because ______. most damage is repaired before it is passed on to progeny mutated DNA cannot be replicated, so it cannot be passed to progeny damage to DNA is a very uncommon event
most damage is repaired before it is passed on to progeny
A bacterium spontaneously developing resistance to 2 different types of antibacterial medications is ______ it developing resistance to just one of them. much more likely than equally likely to much less likely than
much less likely than
An actual DNA transformation experiment is set up so that _______ grow under selective conditions. only nontransformed cells both transformed and nontransformed cells only transformed cells
only transformed cells
The__________________ is the observed characteristics of an organism.
phenotype
Mutation rates are low because proofreading and______________ mechanisms fix altered or damaged DNA before it can be passed to progeny.
repair
Thymine dimers can kill cells if left unrepaired, as they cause kinks in DNA that interfere with the processes of_____________ and______________ .
replication; transcription
Dr. Barbara McClintock determined that variegation in the color of corn kernels was due to the insertion of ______ elements into genes involved in pigment synthesis. transposable bacteriophage intercalating retroviral
transposable
Segments of DNA that can move to new positions within the genome of a single cell are called___________
transposons
In the most thoroughly studied example of bacterial conjugation, the term_____________ designates a donor cell with an F plasmid, whereas those cells who lack the F plasmid are termed______________ .
F+ ; F-
True or false: A point mutation always leads to a shift of the reading frame from the point of mutation downstream.
False
_____________mutations are genetic changes caused by factors from outside of the cell such as radiation or chemicals.
Induced
_______ is the transfer of bacterial DNA from a donor to recipient via a bacteriophage. Transduction Conjugation Transformation Transposition
Transduction
_____________ ______________are a type of radiation that can cause single and double stranded breaks in a DNA strand.
x rays
X rays can cause which types of damage to a DNA molecule? Double stranded breaks Nucleobase alterations Single stranded breaks Thymine dimer formation
Double stranded breaks Nucleobase alterations Single stranded breaks
Sometimes DNA polymerase adds the wrong nucleotide to the growing chain. If proofreading does not fix the error, then it is usually fixed by a mechanism called________________ repair.
mismatch
How many strands of donor DNA integrate into a recipient chromosome during transformation? One Two None
One
A bacterial virus is known as a(n) _______. phage retrovirus prion bacteriovirus elementary body
phage
Which of the following are components of the simplest transposon, an insertion sequence? inverted repeats origin of replication transposase gene reverse transcriptase antibiotic resistance gene
inverted repeats transposase gene
_____________agents insert themselves between adjacent base pairs in a DNA strand, increasing the rate of frameshift mutations.
Intercalating
CRISPR systems involve ______. enzymes that recognize and cut at a specific sequence of nucleotides enzymes that protect bacterial cells from cold temperatures retained segments of phage DNA used by bacteria to recognize and destroy future invading DNA
retained segments of phage DNA used by bacteria to recognize and destroy future invading DNA
After new virus particles have assembled in the bacterial host cell, they are usually ______. destroyed by the bacterial immune system released as a result of host cell lysis integrated into the structure of the bacterial cell wall stored inside the cell for a later time
released as a result of host cell lysis
______ repair is activated by extensive DNA damage and uses a polymerase that lacks proofreading ability, ultimately resulting in mutations. Proofreading Photoreactivation Mismatch SOS Excision
SOS
Which of the following are characteristics of recombinants? . The have properties of both donor and recipient cells. They result from horizontal gene transfer. They are genetically identical to their parent strain. They have multiple chromosomes.
The have properties of both donor and recipient cells. They result from horizontal gene transfer.
In penicillin enrichment, the penicillin selects against the ______ which can grow in the medium. auxotrophs prototrophs heterotrophs chemotrophs
prototrophs
In generalized transduction, donor DNA is mistakenly packaged into a phage coat, forming a______________ particle.
transducing
When two bacterial strains that are His-/Trp- (require his and trp for growth) and Leu-/Thr- (require leu and thr for growth) are mixed together and plated on minimal media, any colonies that form are likely due to one strain acquiring genes from another strain. This is called_____________ gene transfer.
horizontal
During transduction, donor DNA is injected into a recipient cell by a phage. This DNA integrates into the recipient's chromosome by_________________ .
homologous; recombination
How does a modification enzyme protect a bacterial cell from its own restriction enzyme? By ligating together cuts in the cell's DNA made by the restriction enzyme By binding to the DNA as a repressor protein, thereby blocking transcription of the restriction enzyme By competitively inhibiting the activity of the restriction enzyme By adding methyl groups to the nucleobases of the cell's DNA that are recognized by the restriction enzyme
By adding methyl groups to the nucleobases of the cell's DNA that are recognized by the restriction enzyme
Which of the following are replicons? Chromosome fragment Chromosome Plasmid
Chromosome Plasmid
When an excision errors produces a plasmid containing both chromosomal and F plasmid DNA, the resulting plasmid is called a(n)_______________ plasmid.
F'
When integrated F plasmid DNA in an Hfr cell is excised from the chromosome, an excision error can result in the removal of chromosomal DNA along with the F plasmid DNA, creating a plasmid called ______. F' F+ F- Hfr
F'
__________________selection is used to isolate an auxotroph from a prototrophic parent strain, because no selective medium exists to inhibit the parent
Indirect
__________________selection is used to isolate an auxotroph from a prototrophic parent strain, because no selective medium exists to inhibit the parent.
Indirect
Which is an agent that induces changes in DNA? Mutagen Mutant Mutation
Mutagen
Which term refers to an organism that has a mutation? Mutagen Mutant Wild type
Mutant
Which of the following statements best describes mutation rates of genes? They range between one in 10,000 and one in a trillion. They are commonly as low as zero. They range between one in 10 and one in 100. They do not occur randomly.
They range between one in 10,000 and one in a trillion.
In E. coli, less than 50% of the genes are found in all strains. These conserved genes are called the_____________ genome.
core
The genes that are present in all strains of a given species are called the ______. plasmid genome pan genome core genome basal genome
core genome
In transformation, only one daughter cell inherits donor DNA. This is because ______. the other daughter cell rejects the donor DNA strand the parent cell keeps one strand of donor DNA and donates the other to one daughter cell. only a single strand of donor DNA integrates into the recipient chromosome
only a single strand of donor DNA integrates into the recipient chromosome
During a viral infection of a bacterial cell, the viral DNA can be integrated into the host chromosome. The DNA is then called a(n)____________ .
prophage
Neither strain A (His-/Trp-) nor strain B (Leu-/Thr-) can grow on minimal media on their own because they cannot synthesize the indicated amino acids. If the strains are mixed and then plated onto minimal media, any colonies that form ______. are likely to be spontaneous mutants should be a result of horizontal gene transfer do not use any of those amino acids for growth
should be a result of horizontal gene transfer
Some types of bacteria become competent ______. when nitrogen and carbon sources are plentiful when there is a high concentration of bacterial cells when there is a low concentration of bacterial cells when nitrogen or carbon sources are scarce
when there is a high concentration of bacterial cells when nitrogen or carbon sources are scarce
During repair of oxidized guanine, which enzyme removes the damaged nucleobase from the sugar-phosphate backbone? RNA polymerase DNA polymerase DNA glycosylase helicase DNA ligas
DNA glycosylase
Which of the following can be found in a bacteriophage? DNA or RNA genome hybrid DNA/RNA genome protein genome lipid membrane nucleus protein coat
DNA or RNA genome protein coat
______ sometimes incorporates the incorrect nucleotide when generating a new strand of DNA during DNA ______; this leads to a detectable distortion in the DNA helix. RNA polymerase; replication DNA polymerase; transcription RNA polymerase; transcription DNA polymerase; replication
DNA polymerase; replication
In humans, two of the genes associated with the development breast cancer encode enzymes involved in ______. DNA repair mutagenesis DNA damage cell death
DNA repair
After transfer of the F plasmid is complete, both the donor and recipient cells are now considered_______________ , so they can act as donors of the F plasmid.
F+
Mutants that can grow under conditions in which the parent (wild type) cells cannot are easily isolated by____________ selection.
direct
Penicillin_______________ is a technique in which mutant cells are incubated in glucose-salts broth with penicillin before plating on nutrient agar in order to increase the ratio of auxotrophs to prototrophs.
enrichment
Proteins that remove thymine dimers without light are termed repair enzymes.
excision
In the Ames test, it is expected that a mutagen would ______ the reversion rate of of a histidine-requiring auxotroph of Salmonella. decrease increase have no effect on
increase
Replica plating is used in ______ selection to transfer an identical pattern of bacterial cells to both a nutrient agar and a glucose-salts agar plate. direct degenerate indirect differential
indirect
In an experiment, donor DNA, DNase, and recipient cells are added to a mixture. The recipient cells are not transformed. This tells us what about the donor DNA? It is contained within bacteriophages. It is contained within cells. It is naked.
it is naked
Some prokaryotes are naturally competent ______. at random times during their growth when their DNA is damaged only under specific conditions all the time
only under specific conditions all the time
A replicon is a DNA molecule that contains a(n) ____________of____________ .
origin; replication
The sum total of genes encoded by all strains of a given species is called the_______________ -_____________________.
pan genome
Genomic islands that contain genes that increase the disease-causing abilities of the bacterium are called ______ islands. fertility virulence pathogenicity composite resistance
pathogenicity
Bacteria are a great model system for genetic studies because when they are grown to very high numbers in small volumes of simple media ______. rare genetic changes that happen can be easily studied the genetic makeup of the population is very stable and never mutates the bacteria divide indefinitely so the population number remains constant
rare genetic changes that happen can be easily studied
Base substitutions are more common in aerobic vs. anaerobic environments because of the production of ______ under aerobic conditions. reactive oxygen species DNA polymerase guanine nucleotides ATP
reactive oxygen species
These chemicals, produced in aerobic environments, result in increased base substitution because they oxidize guanine in DNA. quaternary ammonium compounds major histocompatibility complexes (MHC) reactive oxygen species (ROS) intercalating agents
reactive oxygen species (ROS)
A(n)_______________ mutation is a base substitution that does not change the encoded amino acid.
silent
A base substitution in a protein-encoding gene results in one of three possible mutation outcomes:______________ mutation, ____________mutation, or ____________mutation.
silent; missense; nonsense
______ plasmids encode resistance to a variety of antimicrobial agents and heavy metals. F A X Ti R
R
The consequences of not repairing damaged DNA in cells include ______. cells that have fewer mutations increased activity of RNA polymerase cell death cancer (in animals)
cell death cancer (in animals)
Although mobilizable plasmids encode an origin of transfer, they lack other genetic information required for transfer. Under what circumstances can a mobilizable plasmid be transferred to another bacterial cell? when the mobilizable plasmid is present in a Gram-negative cell when the mobilizable plasmid is present in a Gram-positive cell when a conjugative plasmid is present in the same cell when two different mobilizable plasmids work together to transfer
when a conjugative plasmid is present in the same cell
Examples of conditions where bacteria can become naturally competent in the environment include ______. when there is a high density of bacteria when the bacterial DNA is damaged when they are exposed to extreme heat when certain nutrients are scarce
when there is a high density of bacteria when certain nutrients are scarce
Restriction-modification systems of bacteria include what two components? A restriction enzyme that recognizes and cuts at a short nucleotide sequence Modification enzymes that alter the structure of incoming DNA A modification enzyme that adds protective methyl groups to the cell's own DNA Restriction proteins that prevent DNA from getting through pores in the membrane
A restriction enzyme that recognizes and cuts at a short nucleotide sequence A modification enzyme that adds protective methyl groups to the cell's own DNA
What are some of the disadvantages of the SOS DNA polymerase? It competes with the standard DNA polymerase. It has no proofreading ability. It can result in many mutations in the DNA. It only works on undamaged DNA.
It has no proofreading ability. It can result in many mutations in the DNA.
In an experiment, donor DNA, DNase, and recipient cells are added to a mixture. The recipient cells are not transformed. This tells us what about the donor DNA? It is contained within bacteriophages. It is naked. It is contained within cells.
It is naked.
______ is used to fix nucleotide incorporation errors that are missed by the proofreading function of DNA polymerase. Photoactivation Excision repair Polymerase repair Mismatch repair SOS repair
Mismatch repair
Errors by DNA polymerase that incorporate the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanisms? Mismatch repair Photoactivation Excision repair SOS repair Proofreading by DNA polymerase
Mismatch repair Proofreading by DNA polymerase
When treating tuberculosis, two or more antimicrobial medications are often prescribed because ______. a sensitive cell is unlikely to become resistant to two medications simultaneously through separate spontaneous mutations taking only one type of medication greatly increases the mutation rate of the bacteria
a sensitive cell is unlikely to become resistant to two medications simultaneously through separate spontaneous mutations
Because CRISPR systems involve bacteria using retained segments of DNA to identify and destroy future invading phage DNA, these systems are a form of ______. predictive modeling innate immunity adaptive immunity
adaptive immunity
Base ______ structurally resemble nucleobases and can be mistakenly incorporated into nucleotides and then into DNA. analogs adapters pairs donors
analogs
Many bacteria are able to recognize and destroy invading DNA. It is thought this ability evolved ______. during host-pathogen competition with mammalian hosts as a defense against phages as a defense against prions from competition among species of bacteria
as a defense against phages
A mutant which needs a particular nutrient to grow which the normal strain does not is called a(n)______________ .
auxotroph
In replica plating, colonies from the master plate that grow on the nutrient agar plate but not on the glucose-salts plate are ______. auxotrophs prototrophs pseudotrophs minimalists
auxotrophs
In the Ames test, ______ are exposed to a possible mutagen and are then plated onto ______ medium to test for reversion. prototrophs; glucose-salts auxotrophs; glucose-salts auxotrophs; nutrient agar prototrophs; nutrient agar
auxotrophs; glucose-salts
What happens after an F+ donor transfers a strand of an F plasmid to an F- recipient? both become F- It is not possible to predict the outcome. The donor becomes F- while the recipient becomes F+. both become F+
both become F+
Replica plating _______. employs a medium on which the mutant will grow but the parental cell type will not, and so is useful for identifying auxotrophs is useful for direct selection of antibiotic resistance and allows for the identification of prototrophs is useful for direct selection of antibiotic resistance and allows for the identification of auxotrophs employs a medium on which the mutant will not grow but the parental cell type will, and so is useful for identifying auxotrophs employs a medium on which the mutant will grow but the parental cell type will not, and so is useful for identifying prototrophs
employs a medium on which the mutant will not grow but the parental cell type will, and so is useful for identifying auxotrophs
A common consequence of a_____________ mutation is the appearance of an early stop codon that produces a shortened and thus non-functional protein.
frameshift
A(n)__________________ mutation results from an insertion or deletion of nucleotides, leading to a shift of the reading frame from the point of mutation downstream.
frameshift
Which of the following are caused by chemical mutagens? frameshift mutations base substitutions double stranded breaks thymine dimers
frameshift mutations base substitutions
The type of transduction that can transfer any genes of a host cell is called ______ transduction. localized specialized randomized generalized
generalized
Consider a population of bacteria susceptible to an antimicrobial. If a bacterium acquires a spontaneous mutation that gives resistance to the antimicrobial, this bacterium will ______ if the population is exposed to the antimicrobial. grow as well as all the other bacteria not grow as well as all the other bacteria grow without competition
grow without competition
During horizontal gene transfer in bacteria, the transferred donor DNA may be integrated into the recipient's genome via a process called ______. heterologous conversion chromatid exchange nonhomologous end joining homologous recombination
homologous recombination
Once donor DNA is in a recipient cell, it integrates into that cell's chromosome by ______. indirect selection DNA ligase transpositional insertion homologous recombination
homologous recombination
Neither strain A (His-/Trp-) nor strain B (Leu-/Thr-) can grow on minimal media on their own because they cannot synthesize the indicated amino acids. If the strains are mixed and then plated onto minimal media, any colonies that form ______. do not use any of those amino acids for growth are likely to be spontaneous mutants should be a result of horizontal gene transfer
should be a result of horizontal gene transfer
During conjugation, the F plasmid nucleic acid that transfers is ______. double-stranded DNA single-stranded RNA double-stranded RNA single-stranded DNA
single-stranded DNA
Mutations that arise naturally during cellular metabolism, and not as a result of exposure to mutation-causing agents, are called____________ mutations.
spontaneous
Base ______ mutations occur when an incorrect nucleotide is incorporated in place of another during DNA synthesis. translocation substitution deletion insertion
substitution
The most common type of mutation is base_____________ , where an incorrect nucleotide is incorporated during DNA replication.
substitution
Chromosomal DNA is transferred with F plasmid DNA in an Hfr cell because ______. the chromosomal DNA is fragmented into segments the plasmid DNA is integrated into the chromosome in these cells the plasmid DNA and chromosomal DNA are similar in size the chromosomal DNA is homologous with the plasmid DNA
the plasmid DNA is integrated into the chromosome in these cells
Spontaneous mutations are important because ______. they allow populations of bacteria to adapt to a changing environment they allow horizontal gene transfer between bacteria
they allow populations of bacteria to adapt to a changing environment
Ultraviolet radiation causes covalent bonds to specifically form between adjacent_______________ molecules on a DNA molecule.
thymine
___________________transduction results from a packaging error during the virus replication cycle, when a piece of bacterial DNA is included in the new virus particle.
Generalized
Plasmids with a _____________copy number occur in only one copy per cell, while those with a________________ copy number are present in many copies per cell.
low high
The enzymes of the mismatch DNA repair mechanism distinguish between the template strand and the newly synthesized strand by the presence of a(n) ______ group on certain nucleobases of the template strand. carboxyl phosphate methyl amino hydroxyl
methyl
If a base substitution changes an amino acid-encoding codon to a stop codon what would it be called? frameshift mutation nonsense mutation silent mutation deletion mutation missense mutation
nonsense mutation
Which of the following descriptions explain how CRISPR systems function? Transcripts from CRISPR array are used to identify invading DNA with the same sequences, targeting it for destruction by nucleases. Pieces of invading DNA are saved in a chromosomal region called CRISPR array. Enzymes rearrange bacterial gene sequences to produce a variety of transcripts used to identify and target invading DNA for destruction. Cells analyze invading DNA sequences in order to predict and destroy new, different sequences they might encounter.
Transcripts from CRISPR array are used to identify invading DNA with the same sequences, targeting it for destruction by nucleases. Pieces of invading DNA are saved in a chromosomal region called CRISPR array.
Which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells? Conjugation Transduction Transposition Transformation
Transformation
Which of the following statements about transformation is correct? Transformation depends on a donor cell containing an F plasmid and a recipient cell that does not. Transformation is the uptake of naked DNA from the environment. Transformation involves the formation of a sex pilus through which plasmid DNA is shared between bacteria. Transformation is the transfer of DNA from one bacterial cell to another by means of a bacteriophage.
Transformation is the uptake of naked DNA from the environment.
The easiest way to detect if streptomycin sensitive (StrS) cells are transformed with DNA from streptomycin resistant cells (StrR) is by growing the cells on ______. a medium containing streptomycin a rich medium like TSA (trypticase soy agar) a minimal medium like glucose-salts agar
a medium containing streptomycin
During bacterial conjugation, synthesis of a new strand of F plasmid DNA occurs in ______. the recipient only neither the donor nor the recipient both the donor and recipient the donor only either the donor or the recipient, but not both
both the donor and recipient
Unlike standard DNA polymerases, the DNA polymerase used in SOS repair ______. can proofread DNA can call on other DNA polymerases for help can synthesize DNA even in very damaged regions
can synthesize DNA even in very damaged regions
Restriction-modification systems were discovered ______. during efforts to develop vaccines for common viral infections in all three domains of life in yeast strains that capable of fermenting a wide array of substrates while studying why certain bacterial strains are relatively resistant to phage infection
while studying why certain bacterial strains are relatively resistant to phage infection
Extensively damaged DNA activates the_____________ repair mechanism, which cannot always determine the correct nucleotide sequence, thus introducing mutations resulting from the repair process itself.
SOS
Chromosomal DNA that is transferred from an Hfr cell but does not integrate into the recipient's chromosome ______. replicates circularizes is translated is degraded
is degraded
Recognition and repair of errors in nucleotide incorporation by DNA polymerase is called ______. excision repair proofreading photoactivation mismatch repair
proofreading
When horizontal gene transfer occurs between a donor and recipient cells, the resulting cells are called________________
recombinants
When bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses ______. after the components are released from the host cell within that cell before being released within the nucleus of the host cell before release when the bacterial cell enters a new eukaryote host
within that cell before being released
The CRISPR system has been called the immune system of bacteria. It helps protect bacteria from a repeat infection because bacterial cells ______. modify the attachment sites for the phages so that new infections cannot take place recognize proteins on the surface of the phage and secrete proteins that block the binding of the phage recognize proteins on the surface of the phage and secrete enzymes that digest the phage integrate phage DNA fragments in their own chromosomes and target for destruction any DNA encountered later that contains the same sequences integrate fragments from the phage RNA in their own chromosomes and target for destruction any RNA that contains the same fragments in the future
integrate phage DNA fragments in their own chromosomes and target for destruction any DNA encountered later that contains the same sequences
